The invention relates to a method of operating an inductor and to an inductor for carrying out such method.
In the prior art, an inductor is water cooled during operation. For this purpose, an induction coil has a hollow cross-section which defines a cooling passage (see EP 0 291 289 B1, EP 0 339 837 B1). Such water cooling serves to protect the inductor against overheating. Water cooling has, however, the disadvantage that any leaks result in potentially harmful and in any event undesired steam generation on discharge into a melt.
DE 41 36 066 A1 discloses a discharge device for a metallurgical vessel and a method of opening and closing a discharge or outlet sleeve. An inductor is to be moved relative to the discharge sleeve into different displacement positions in order to influence thermal conduction between the inductor and the discharge sleeve. In a first displacement position, a gap between the inductor and the discharge sleeve constitutes heat insulation and the electrically switched on, cooled inductor inductively melts a metal plug in the discharge sleeve. In the second displacement position, there is a thermally conductive connection between the inductor and the discharge sleeve. The inductor through which cooling medium flows is electrically switched off. The cooling down of the discharge sleeve which thus occurs permits the metal melt to freeze in the discharge sleeve. In order to be able to operate the inductor in both these working phases (displacement positions) it must be mechanically moved. This requires an appropriate actuation and control device.
An inductor at an outlet element of a melt vessel is described in German Patent Application P 44 28 297 and is installed directly in the base of a melt vessel or in an apertured brick in the base of the melt vessel. This inductor cannot be operated in a manner corresponding to DE 41 36 066 A1 because it cannot be moved with respect to the discharge sleeve.